1. Field of the Invention
The present invention relates to a positioning device suitable for positioning a body adjacent a contiguous target area.
2. Description of the Prior Art
Chest X-rays are a basic diagnostic tool for treating diseases or injuries of the thorax. To obtain a chest X-ray, the patient typically stands in front of a film holder containing a sheet of film sufficiently large to extend from the neck to the diaphragm and to each side of the chest. The patient is then exposed to radiation to obtain an X-ray image on the film.
It is well recognized that the diagnostic effectiveness of a chest X-ray depends in great measure on the proper positioning of the patient. It is important that the patient be centered on the film sheet.
For this purpose, various types of positioning apparatii are in use. One such apparatus shines a pattern of light along the axis of the radiation beam onto the patient. The pattern of light has a frame, cross-hairs or other aiming means for positioning the patient, film holder, and X-ray generator. Another type of apparatus uses lines of light to indicate the edges of the film sheet.
Because of concern over the health hazards of X-rays, exposure control devices have come into use. These devices may typically be ionization chambers positioned behind the X-ray film sheet for alignment with the lung fields of the patient. When a predetermined amount of radiation has been received by the exposure control devices, exposure is automatically terminated.
Problems have heretofore arisen with automatic exposure control systems when used with existing positioning systems due to improper positioning of the patient. When taking a posterior-anterior chest X-ray, the spinal column of the patient may become located over one of the exposure control devices. The density of the spinal column is greater than that of the lungs so that the operation of the exposure control device is altered, typically resulting in over exposure of the film. Not only is the patient over exposed on the initial chest X-ray, this over exposure often requires a retake, further increasing the amount of radiation to which the patient is exposed.